Pretty good review. I have long been a Beretta fan, but when I first saw photos of the APX I thought that the slide with its cheese grater charging handles/cocking serrations was frighteningly ugly. It looks somewhat less so in the video. I wonder how much these aggressive serrations might interfere with holstering the weapon, or how much they might chew up a leather holster.
I like that the interchangeable back straps actually wrap around onto the sides of the magazine receiver. The interchangeable back straps on the Gen 4 Glocks do nothing for me because they do not alter the shape or width of the grip, only the anterior-posterior dimension.
Regarding the firing pin block rising up out of the slide, this is a pretty common feature of Berettas. The 92 series has it, the Cougar had it (although the block is rectangular in those), the PX4 Storm has it. I can see how it might be an issue fitting an optic.
Having to drive out a pin to take out the chassis is certainly a bit more cumbersome than removing the FCU on the P320.
The thing I really don't get is the "bullet button" striker decocker. Certainly, too many people have accidentally shot themselves or someone else field stripping pistols like Glocks which require a trigger pull to remove the slide because they forgot to clear the chamber. But if you are going to remember to pull the slide back and find something small and pointy enough to push the decocker button in, wouldn't you remember to clear the chamber? And wouldn't it be easier to do so?
The pistol seemed to handle recoil very nicely, but you would expect that of a 9 mm of this size and weight. All in all, I have a much more positive feel about the APX after watching the video. I would like to try shooting one, if I get the chance.